Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

readOnlyHint=true already covers the safety profile, so the description's job is to add context — and it does, by linking the returned template ids to the custom_template_id parameter of invoice creation, which is cross-tool information annotations cannot carry. It doesn't say whether other account fields come back, but for a read-only, zero-argument call that is a small gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

One sentence, front-loaded with what is read, followed by the actionable hint about the ids. No filler and nothing repeated from the annotations.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no parameters and no output schema, the description must convey what comes back; it names the API version and custom invoice templates but leaves it ambiguous whether additional account data is returned. Adequate for a trivial read tool, short of fully specifying the response.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is nothing to document; baseline is 4. The description instead documents the output's usable values (custom_template_id), which is the relevant semantic for a no-arg call.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb and resources: reads the API version and the account's custom invoice templates. The parenthetical explains what the template ids are for, which disambiguates it from the entity getters and list tools in the sibling set. It is clear, though the generic tool name 'get_info' means the description has to do more work than a well-named tool would.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The parenthetical implies when the result matters (before creating an invoice with a custom template), but the description never states when to call this tool versus alternatives or that it takes no arguments and is safe to call freely. Usage is inferred rather than instructed.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.